PezCycling News - What's Cool In Pro Cycling : Cadence: Effect on Subsequent Max Effort?

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Cadence: Effect on Subsequent Max Effort?
We’re often taught to spin our legs during the early parts of the race in order to “save” our legs for the hard efforts near the end. However, this spinning at easier wattages often comes at a higher energy cost than at a lower cadence. So is it indeed the best option prior to attacking the final crunch point of the race?

Pedals Keep Turning
We have covered a lot of concepts and a lot of studies here in Toolbox over the past couple of years concerning optimal cadence. Most have been somewhat equivocal about a higher cadence being better or more efficient when hammering at high intensities. Studies like Foss and Hallen’s in 2004 and 2005 (1, 2) suggest that there was no difference in efficiency at 80, 100, or 120 rpm when riding at very high intensities to exhaustion.

This has been followed by Mora-Rodriguez et al.’s 2006 study on optimal cadence (4). This study also found that minimal difference was evident in efficiency at 80, 100, or 120 rpm. If anything, the higher cadence actually cost a bit more in energy consumption. Two theories proposed for this possibly increased inefficiency at high cadences included the extra energetic cost of turning the legs over more frequently and also the possible increased recruitment of fast twitch fibres.

Leadout Train to Crunch Time
While the above studies may give us good ideas about what to do during sustained high intensity efforts such as time trials, hill climbs, or prologues, it is not always directly applicable to typical road race situations. Namely, most races feature prolonged efforts at relatively low wattages, followed by a serious crunch time of maximal effort.

Traditional advice is that we should save our legs during the early parts of the race by spinning as much as possible in easy gears. By doing so, our legs are fresher and have more snap to them when the going gets tough. However, what we do know from scientific studies is that, at relatively easy wattages, there is a rough U-shaped relationship between cadence and energetic cost, such that the optimal pedaling rate (OPR), at which the energetic costs are lowest, is typically in the range of 40-75 rpm. This is obviously much lower than the typical Freely Chosen Pedaling Rate (FCPR) of 90-100 rpm that most of us ride at. So while there may be other good reasons for riding at this cadence range, it is not the most energetically efficient one.

Therefore, this sets up an interesting question explored in a new study by Hansen et al. (3) in the October issue of Eur J Appl Physiol: is there an effect of prolonged submax riding at the OPR versus FCPR on subsequent maximal 5 min performance? From a practical perspective, does the extra energetic costs of a higher FCPR during the first “easy” part of a race impair my ability to hammer at the end of a race?

General Study Details
• Nine well-trained cyclists served as subjects. No real detail on the actual physical characteristics were provide. However, the average 5 min wattage of 399 W suggests that they were trained by not elite cyclists.

• On the first day, they determined their OPR by riding at 180 W at 35, 50, 65, 80, 95 rpm and at FCPR. 180 W was chosen to represent a relatively easy and typical endurance effort for elite cyclists, especially when riding in the shelter of a peloton.

• After a rest break, subjects then rode as hard as possible for 5 min at FCPR, a time and effort replicating the decisive parts of a race (e.g., bridging to a break, solo break, crosswind).

• On the two experimental days, subjects pedaled for 2.5 h at either OPR or FCPR. They then rode as hard as possible at FCPR for 5 min.

General Results
• Mean OPR from the first test session was 73 +/- 11 rpm, with a range of 65-95 rpm. This demonstrates huge individual variability! In contrast, FCPR was 95 +/- 7 rpm.

• During the 2.5 h of cycling at 180 W, oxygen uptake was slightly (7%) higher with the FCPR.

• In both cases, mean power output during the 5 min effort was lower after 2.5 h cycling (8% in OPR, 368W; and 10% in FCPR, 359W) compared to the initial baseline day (399W). There were no differences between OPR and FCPR.

• The main difference in the 5 min efforts between 2.5 h of OPR or FCPR was that peak oxygen uptake following FCPR compared to the baseline 5 min effort. This could suggest that 2.5h of FCPR may be less efficient to the point of possibly becoming practically significant. So with greater subject numbers, the 9 W difference between OPR and FCPR may become actually significant statistically.

Taking it to the Road
So given what we have seen in this study, it appears that it doesn’t make a huge difference whether you spend the time cruising in the peloton at either a high cadence or a metabolically more efficient lower cadence. In both cases, you are going to get tired and you’re not going to be able to hammer as hard when the “fox gets into the henhouse.” However, while nothing was statistically significant, the trend is actually that spinning your legs may be more inefficient and impair your ability to make the decisive move.

In closing, I will again reiterate my main mantra with these cadence articles: it’s more important to be efficient at your “normal” or “optimal” cadence than having a higher cadence just for the sake of a higher cadence.

Related Stories

Pedaling Cadence and Efficiency: we examine 2005 and 2006 studies on optimal cadence.

Foss and Hallen 2004 and 2005 studies on optimal cadence
We examine Lance’s improvements in pedaling efficiency from 1993 through his first Tour victory

We analyze another Spanish study that finds pedaling efficiency much more important than what your VO2max is

References

1. Foss, O. and J. Hallen. Cadence and performance in elite cyclists. Eur J Appl Physiol. 93:453-462, 2005.
2. Foss, O. and J. Hallen. The most economical cadence increases with increasing workload. Eur J Appl Physiol. 92:443-451, 2004.
3. Hansen, E. A., K. Jensen, and P. K. Pedersen. Performance following prolonged sub-maximal cycling at optimal versus freely chosen pedal rate. Eur J Appl Physiol. 98:227-233, 2006.
4. Mora-Rodriguez, R. and R. Aguado-Jimenez. Performance at high pedaling cadences in well-trained cyclists. Med Sci Sports Exerc. 38:953-957, 2006.




About Stephen:
Stephen Cheung is an Associate Professor of Kinesiology at Dalhousie University, with a research specialization in the effects of thermal stress on human physiology and performance. He can be reached for comments at stephen@pezcyclingnews.com.

 

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